CN112844386B

CN112844386B - Preparation method and application of trace boron-doped cobalt oxyhydroxide

Info

Publication number: CN112844386B
Application number: CN202011559895.4A
Authority: CN
Inventors: 邓林; 施周; 曾寒轩
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2020-12-25
Filing date: 2020-12-25
Publication date: 2021-12-24
Anticipated expiration: 2040-12-25
Also published as: CN112844386A

Abstract

The invention relates to a preparation method and application of trace boron-doped cobalt oxyhydroxide.A cobalt-aluminum hydrotalcite powder is dispersed in water to obtain a suspension A; uniformly mixing borohydride, strong base and water to obtain a mixed solution; mixing the suspension A and the mixed solution, and stirring until complete reaction to obtain a suspension B; and sequentially filtering, washing and drying the suspension B to obtain trace boron-doped cobalt oxyhydroxide (B-CoOOH). Compared with CoOOH prepared by a conventional method, namely a precipitation method, B-CoOOH has stronger catalytic efficiency and more stable physical and chemical structure in the application of catalytic degradation of sulfamethoxazole, the elution amount of heavy metal Co is extremely low, secondary pollution to a water body can be avoided in the practical application, and the method is safe and environment-friendly.

Description

Preparation method and application of trace boron-doped cobalt oxyhydroxide

Technical Field

The invention relates to a preparation method and application of trace boron-doped cobalt oxyhydroxide, belonging to the field of material preparation.

Background

The drugs and Personal Care Products (PPCPs) are a kind of new organic pollutants including various antibiotics, anti-inflammatory and antibacterial drugs, hair Care Products, etc., and the rapid development of the biopharmaceutical industry brings benefits to human life and health and also embeds unstable factors for the safety of ecological environment. A large amount of PPCPs substances which are not absorbed and metabolized by human bodies flow into natural water bodies through the daily activities of human beings, and because the PPCPs exist in the natural water bodies usually in the form of trace concentration, the PPCPs do not produce acute toxicity to the organisms in a short time. However, PPCPs have extremely high chemical stability and difficult biodegradability, and as the enrichment concentration of the substances in the nature is gradually increased, the high-exposure trilinearity can have serious influence on organisms. Therefore, development and research are urgently needed for the removal technology of the substances.

At present, the methods for removing the trace PPCPs in water mainly comprise physical, chemical and biological methods. Unfortunately, conventional physical adsorption and biodegradation methods are not ideal for the removal of PPCPs. Meanwhile, the rise of the advanced oxidation process based on the strong oxidizing free radicals provides a new idea for the rapid removal of PPCPs, and the advanced oxidation process is a water treatment method for degrading refractory organic matters in water by activating a large amount of active free radicals generated by oxidants such as ozone, hydrogen peroxide, persulfate and the like. Advanced oxidation technologies based on sulfate radicals have recently received particular attention from researchers due to the stronger environmental impact resistance of sulfate radicals over traditional hydroxyl radicals, the choice of oxidation and longer half-life.

Cobalt oxyhydroxide (CoOOH) is a cheap material commonly used in the field of electrocatalysis, and is CoO sandwiched with protons between layers₆Two-dimensional layered catalyst formed by layering and overlapping octahedrons. Researchers have synthesized CoOOH in various forms such as flakes, spheres, rods, and the like by means of alkali precipitation, in situ synthesis, precursor conversion, and the like. Although CoOOH is a relatively efficient and stable oxygen generation (OER) catalyst, it is limited by the catalytic activity of its cobalt sites, and its catalytic efficiency is very low in the field of advanced oxidation water treatment, so researchers usually compound CoOOH with other catalysts to improve the catalytic performance of CoOOH, but the preparation process of these composite materials is generally complicated and not beneficial to mass preparation and practical application.

Disclosure of Invention

Aiming at the defects of the prior art, one of the purposes of the invention is to provide a preparation method of trace boron-doped cobalt oxyhydroxide with good catalytic activity and stable structure; the invention also aims to provide the application of trace boron-doped cobalt oxyhydroxide in degrading PPCPs in water.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a preparation method of trace boron-doped cobalt oxyhydroxide comprises the following steps:

s1, providing cobalt aluminum hydrotalcite;

s2, dispersing the cobalt-aluminum hydrotalcite in water to obtain a suspension A; optionally ultrasonic dispersing;

uniformly mixing borohydride, strong base and water to obtain a mixed solution;

s3, mixing the suspension A and the mixed solution, and stirring until complete reaction to obtain a suspension B;

and S4, sequentially filtering, washing and drying the suspension B to obtain trace boron-doped cobalt oxyhydroxide (B-CoOOH).

Further, in S1, the preparation method of the cobalt aluminum hydrotalcite comprises the following steps:

(1) dissolving water-soluble cobalt salt, water-soluble aluminum salt and urea in water to obtain a transparent solution;

wherein the molar ratio of the water-soluble cobalt salt to the water-soluble aluminum salt to the urea in the transparent solution is 8-12:1:45-55, further 9-11:1:48-52, and further 10:1: 50; preferably, ultrasonic dissolution is adopted, and optionally ultrasonic treatment is carried out for 8-15 min;

(2) condensing and refluxing the transparent solution obtained in the step (1) in an oil bath at the temperature of 95-99 ℃ for 2.5-3.5h, and then sequentially carrying out solid-liquid separation, washing and drying to obtain cobalt-aluminum hydrotalcite powder; optionally, when washing, the washing is carried out by alternately washing with absolute ethyl alcohol and water.

Optionally, the water-soluble cobalt salt is cobalt nitrate; optionally, the water-soluble aluminum salt is aluminum nitrate.

Optionally, the molar ratio of the water-soluble cobalt salt, the water-soluble aluminum salt, the urea and the water in the transparent solution is 8-12:1: 45-55: 30-40.

Alternatively, in step (2), the reaction was refluxed for 3h in an oil bath at 97 ℃.

Further, in S2, the mass-volume ratio of the cobalt-aluminum hydrotalcite to the water is 0.01-0.03 g: 5 to 10mL, further 0.015 to 0.025g, 8 to 12mL, preferably 0.02 g:8 mL.

Further, in S2, the molar volume ratio of the borohydride, the strong base and the water is 0.005-0.011 mol: 0.05-0.11 mol: 65-78mL, further 0.006-0.010 mol: 0.06-0.10 mol: 68-75mL, preferably 0.008 mol: 0.08 mol: 72 mL.

Further, in S2, the borohydride is one or more of lithium borohydride, sodium borohydride, and potassium borohydride.

Further, in S2, the strong base is one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

Further, in S3, stirring is carried out for 10-14h at 28-32 ℃, and magnetic stirring is preferred.

Further, in S3, the volume ratio of suspension A to the liquid mixture was 6-10: 70-75.

Further, in S4, drying is carried out at 58 to 62 ℃, preferably at 60 ℃.

Based on the same inventive concept, the invention also provides the application of the trace boron-doped cobalt oxyhydroxide prepared by the preparation method in degrading PPCPs in aqueous solution.

Further, placing the trace boron-doped cobalt oxyhydroxide and PMS (potassium hydrogen persulfate) in the aqueous solution, and stirring; preferably, 0.05-0.2 g (further 0.1-0.15 g) of trace boron-doped cobalt oxyhydroxide is added into each 1L of the aqueous solution; preferably, the temperature of the aqueous solution is controlled to be 10-45 ℃, further 20-40 ℃, further 25-35 ℃ during the stirring process.

Further, the PPCPs include drugs and personal care products, and further include various antibiotics, synthetic musk, analgesics, hypotensive drugs, contraceptive drugs, hypnotic drugs, weight-loss drugs, hair spray, hair dyes, bactericides and the like.

The invention adopts an in-situ synthesis mode by taking cobalt-aluminum hydrotalcite as a precursor, not only can obtain the cobaltous oxyhydroxide with stable morphology and structure, but also can obviously improve the catalytic activity of the cobaltous oxyhydroxide by doping trace boron.

Mixing a suspension containing cobalt-aluminum hydrotalcite (CoAl-LDH) with an aqueous solution containing borohydride and strong base, and gradually dissolving aluminum in the cobalt-aluminum hydrotalcite in the solution under the etching action of the strong base, wherein cobalt is precipitated as cobalt hydroxide; meanwhile, with the consumption of sodium hydroxide, B generated by the gradual decomposition of borohydride is doped into cobalt hydroxide, hydrogen is generated to deprive oxygen in the cobalt hydroxide to form a large number of oxygen vacancies, and then the cobalt hydroxide with oxygen vacancies is converted into trace boron-doped cobalt oxyhydroxide under the natural oxidation generated by continuous stirring.

The invention degrades PPCPs in water by catalyzing PMS through trace boron-doped cobaltous oxyhydroxide, the mechanism of the invention comprises that amorphous boron is used as an electron transfer intermediate in the catalysis process to accelerate the oxidation reduction of divalent cobalt and trivalent cobalt, and more oxygen vacancies can crack PMS to generate non-free radical active substances.

Compared with CoOOH prepared by a conventional method, the method has the beneficial effects that: (1) B-CoOOH can provide more catalytic active sites; (2) B-CoOOH has richer oxygen vacancy active sites; (3) has a more stable physical and chemical structure, has very low elution amount of heavy metal Co in the catalytic degradation reaction process, can ensure that the secondary pollution to water can not be caused in practical application, and is safe and environment-friendly.

Drawings

FIG. 1 is a scanning electron micrograph of B-CoOOH in example 1.

FIG. 2 is a transmission electron microscopy scanning of B-CoOOH in example 1.

FIG. 3 is an X-ray diffraction pattern of CoAl-LDH and B-CoOOH.

FIG. 4 shows the effect of different substances in catalyzing PMS to degrade sulfamethoxazole.

FIG. 5 is a graph showing the elution amount of heavy metal cobalt when different substances catalyze PMS to degrade sulfamethoxazole.

Detailed Description

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

Example 1

In this example, the trace amount of boron-doped cobalt oxyhydroxide (B-CoOOH) was prepared as follows:

0.260 g of cobalt nitrate, 0.034 g of aluminum nitrate and 0.270 g of urea are mixed and dissolved in 100 mL of ultrapure water, ultrasonic treatment is carried out for 10 minutes, then condensation reflux reaction is carried out for 3 hours in an oil bath at 97 ℃, the obtained precipitate is alternately washed clean by absolute ethyl alcohol and ultrapure water, and then dried at 60 ℃ to obtain cobalt-aluminum hydrotalcite powder, which is collected for standby. And (2) dispersing 0.02g of the obtained cobalt-aluminum hydrotalcite powder in 8mL of ultrapure water, carrying out ultrasonic treatment for 10 minutes, adding 72mL of mixed solution containing 0.008mol of sodium borohydride and 0.08mol of sodium hydroxide, carrying out magnetic stirring at 30 ℃ for 12 hours, filtering to obtain a solid phase, cleaning, and completely drying at 60 ℃ to obtain trace boron-doped cobalt oxyhydroxide.

Comparative example 1

The preparation of boron undoped cobalt oxyhydroxide (N-CoOOH) was similar to that of example 1, with the only difference that: sodium hydroxide solution was used instead of the mixed solution in example 1.

Example 2

A method for degrading PPCPs in water by catalyzing PMS by using catalysts (4 groups according to different types of catalysts, namely B-CoOOH obtained in example 1, N-CoOOH obtained in comparative example 1, CoOOH prepared by adopting a traditional coprecipitation method and CoAl-LDH obtained by adopting the method in example 1) comprises the following specific steps: an aqueous solution containing sulfamethoxazole to be treated was prepared as a solution to be treated (pH =7) in a volume of 50mL and an initial sulfamethoxazole concentration of 40. mu.M (where M is mol/L and. mu.M is 10)^-6mol/L, mM is 10^-3mol/L, the same below), 5 mg of catalyst (mass concentration of 0.1 g/L) was added, followed by 0.3 mM PMS.

In addition, B-CoOOH, PMS alone was used to degrade sulfamethoxazole in the above-mentioned solution to be treated as a control.

The relevant processing results are shown in FIG. 4 and FIG. 5, after 6 min of reaction, the removal rate of sulfamethoxazole in the solution by the B-CoOOH system reaches more than 95%, and the effect is obviously superior to that of CoOOH (N-CoOOH) without doping boron and CoOOH prepared by the traditional coprecipitation method. It is worth noting that although the template precursor CoAl-LDH has the strongest catalytic activity, the elution amount of heavy metal Co in the degradation reaction process is as high as 0.82 mg/L, and the elution amount of B-CoOOH system Co is only 0.06 mg/L, which shows that B-CoOOH not only has higher catalytic activity, but also has a more stable physical and chemical structure, can ensure that no secondary pollution is caused to water body in practical application, and is expected to be reused, thereby reducing the treatment cost.

The foregoing examples are set forth to illustrate the present invention more clearly and are not to be construed as limiting the scope of the invention, which is defined in the appended claims to which the invention pertains, as modified in all equivalent forms, by those skilled in the art after reading the present invention.

Claims

1. A preparation method of trace boron-doped cobalt oxyhydroxide is characterized by comprising the following steps:

s1, providing cobalt aluminum hydrotalcite;

s2, dispersing the cobalt-aluminum hydrotalcite in water to obtain a suspension A;

uniformly mixing borohydride, strong base and water to obtain a mixed solution;

the borohydride is one or more of lithium borohydride, sodium borohydride and potassium borohydride;

and S4, sequentially filtering, washing and drying the suspension B to obtain trace boron-doped cobalt oxyhydroxide.

2. The method of claim 1, wherein in S1, the method of preparing the cobalt aluminum hydrotalcite comprises the following steps:

dissolving water-soluble cobalt salt, water-soluble aluminum salt and urea in water to obtain a transparent solution;

wherein, in the transparent solution, the molar ratio of the water-soluble cobalt salt to the water-soluble aluminum salt to the urea is 8-12:1: 45-55;

and (3) condensing and refluxing the transparent solution in an oil bath at the temperature of 95-99 ℃ for 2.5-3.5h, and then sequentially carrying out solid-liquid separation, washing and drying to obtain the cobalt-aluminum hydrotalcite powder.

3. The method of claim 1, wherein the mass-to-volume ratio of cobalt aluminum hydrotalcite to water in S2 is 0.01 to 0.03 g: 5-10 mL.

4. The method according to claim 1, wherein in S2, the molar volume ratio of borohydride, strong base and water is 0.005-0.011 mol: 0.05-0.11 mol: 65-78 mL.

5. The method according to any one of claims 1 to 4, wherein the strong base in S2 is one or more selected from sodium hydroxide, potassium hydroxide and lithium hydroxide.

6. The method according to any one of claims 1 to 4, wherein the stirring is carried out at 28 to 32 ℃ for 10 to 14 hours in S3.

7. The method according to any one of claims 1 to 4, wherein the drying is performed at 58 to 62 ℃ in S4.

8. Use of trace amounts of boron doped cobalt oxyhydroxide prepared according to the method of any one of claims 1 to 7 for degrading PPCPs in aqueous solution.

9. The use according to claim 8, wherein the trace boron doped cobalt oxyhydroxide and PMS are placed in the aqueous solution and stirred.

10. Use according to claim 9, characterized in that 0.05-0.2 g trace amount of boron-doped cobalt oxyhydroxide is dosed per 1L of said aqueous solution.

11. Use according to claim 9, wherein the temperature of the aqueous solution is controlled to be 10-45 ℃ during stirring.